Regenerative fluid pump and stator for the same

ABSTRACT

A regenerative fluid pump ( 10 ) comprises a rotor having rotor blades for compressing fluid on two fluid flow paths, the first of which extends between a first pump inlet ( 12   a ) and a first pump outlet ( 14   a ), and a second of which extends between second pump inlet ( 12   b ) and a second pump outlet ( 14   b ). The pump comprises a stator comprising a plurality of concentric channels ( 16 ), each of which comprises: a pumping channel portion ( 18 ) along which said rotor blades move for compressing said fluid between an inlet and an outlet of the pumping channel; and a stripper channel portion ( 20 ) (shown in broken lines) which allows movement of said rotor blades from said outlet to said inlet of the pumping channel portion. Each concentric channel ( 16 ) comprises two pumping channel portions ( 18 ) and two stripper channel portions ( 20 ).

The present invention relates to a regenerative fluid pump.

A regenerative fluid pump known hereto is shown schematically in FIG. 3.The prior art pump 100 is a radial regenerative fluid pump whichcompresses fluid on a single fluid flow path extending between an inlet102 and an outlet 104 of the pump. The pump comprises a plurality ofconcentric circumferential channels 105 (represented by concentriccircles in FIG. 3). The channels comprise respective pumping channelportions 106 along which fluid compression takes place and whichtogether form part of the fluid flow path. The channels further compriserespective stripper channel portions 108 (shown in broken lines) whichallow the passage of the pump's rotor blades from the outlets ofrespective pumping channel portions 106 to the inlets thereof.

In operation, fluid enters the pump inlet 102 and is compressed by therotor blades in the radially outermost, or first, pumping channelportion 106 a. At the outlet of the first pumping channel portion, fluidis diverted by a diversion channel 110 (shown by arrows in FIG. 3) tothe inlet of a radially inner, or second, pumping channel portion 106 b.At this time, rotor blades having passed along the first pumping channel106 a move into the radially outermost, or first, stripper channelportion 108 a and back to the inlet of the first pumping channel 106 a.Although most fluid is diverted radially inwardly by the diversionchannel there is some seepage through the stripper channel portion dueto the action of the rotor blades and the pressure gradient from theinlet to the outlet of the stripper channel portion. The stripperchannel portion is made so that there are small running clearancesbetween the walls of the stripper channels and rotor blades passingtherethrough.

Fluid continues along the fluid flow path in the same manner asdescribed above until it reaches the pump outlet 104 and for brevitythis further operation will not be described.

It is desirable in certain circumstances to increase the pumpingcapacity of the regenerative pump 100 described above. FIG. 4 is aschematic view of a further prior art regenerative fluid pump 200 inwhich pumping capacity has been increased. Both pumps 100 and 200 arefour stage pumps but unlike pump 100, pump 200 has two fluid flow pathsbetween two pump inlets 202 a and 202 b and one pump outlet 204. Thepump inlets 202 a and 202 b allow fluid to enter the first pumpingchannel portion 206 a and 206 b, respectively, where compression by therotor blades takes place. This constitutes the first pumping stage ofthe pump and as it will be appreciated, pumping capacity increased bythe use of parallel pumping channel portions 206 a, 206 b. In operation,fluid is diverted from the outlets of both the first and the secondpumping channel portions 206 a, 206 b to the inlet of the third pumpingchannel portion 206 c by first and second diversion channels 210 a and210 b, respectively. Fluid from both the first and the second pumpingchannels 206 a, 206 b is then compressed in the third pumping channelportion 206 c which constitutes the second pumping stage of pump 200.Fluid continues to be compressed along the fluid flow path until itreaches the pump outlet 204, in the same manner as with pump 100 above.The arrangement of pump 200 allows the pumping capacity to be increased.

The problems with pump 200 are that the additional pumping channelportion requires the pump to be larger and more massive, requiringincreased manufacturing. Power requirements also increase andperformance characteristics deteriorate.

It is desirable to provide a regenerative fluid pump with increasedcapacity, without some or all of the above mentioned problems.

The present invention provides a regenerative fluid pump comprising arotor having rotor blades, and a stator comprising a plurality ofconcentric channels which comprise pumping channel portions along whichsaid rotor blades move for compressing fluid between respective inletsand respective outlets of the pumping channel portions and stripperchannel portions for allowing said rotor blades to pass from saidoutlets to said inlets of the pumping channel portions, wherein at leastone of said concentric channels comprises at least two pumping channelportions and at least two stripper channel portions.

The present invention also provides a stator for a regenerative fluidpump comprising a rotor having rotor blades, the stator comprising aplurality of concentric channels which comprise pumping channel portionsalong which said rotor blades move for compressing fluid betweenrespective inlets and respective outlets of the pumping channel portionsand stripper channel portions for allowing said rotor blades to passfrom said outlets to said inlets of the pumping channel portions,wherein at least one of said concentric channels comprises at least twopumping channel portions and at least two stripper channel portions.

Other aspects of the invention are defined in the accompanying claims.

In order that the present invention may be well understood, anembodiment thereof, will now be described, with reference to theaccompanying drawings, in which:

FIG. 1 is a schematic representation of a regenerative fluid pumpembodying the present invention;

FIG. 2 is a schematic representation of another regenerative fluid pumpembodying the present invention;

FIG. 3 is a schematic view of a prior art regenerative fluid pump; and

FIG. 4 is a schematic view of another prior art regenerative fluid pump.

Referring to FIG. 1, a regenerative fluid pump 10 is shown whichcomprises four pumping stages although, more or less stages may beprovided, as required. Pump 10 comprises a rotor (not shown) havingrotor blades for compressing fluid on two fluid flow paths, the first ofwhich extends between a first pump inlet 12 a and a first pump outlet 14a, and a second of which extends between a second pump inlet 12 b and asecond pump outlet 14 b. The pump comprises a stator comprising aplurality of concentric channels 16, each of which comprises: a pumpingchannel portion 18 along which said rotor blades move for compressingsaid fluid between an inlet and an outlet of the pumping channel; and astripper channel portion 20 (shown in broken lines) which allowsmovement of said rotor blades from said outlet to said inlet of thepumping channel portion. Diversion channels 22 (indicated by arrows inFIG. 1) divert fluid between the pumping channel portions in the sameway as the diversion channels described above in relation to FIG. 3.

Differently from the prior art, each concentric channel 16 comprises twopumping channel portions 18 and two stripper channel portions 20. Eachchannel 16 forms part of both fluid flow paths, although atdiametrically opposed parts of the channel. Although each of the pumpingchannel portions 18 in respective concentric channels is shorter(extends over a reduced arc) as compared with the pump shown in FIG. 3,it has been found that most compression takes place over the latterportion of a pumping channel portion and therefore the reduction inlength does not significantly affect compression ratio in the pumpingchannel portions. Accordingly, the capacity of the pump 10 is almostdoubled as compared to the capacity of the pump 100 shown in FIG. 3.Reference is made to the Applicant's co-pending application(GB0215708.9) in which the effect of reducing the length of the pumpingchannel portion length is discussed in more detail.

In operation, fluid enters the first fluid flow path and the secondfluid flow path at first pump inlet 12 a and second pump inlet 12 b,respectively. Fluid on the first fluid flow path is compressed by rotorblades passing along a first pumping channel portion 18 a forming partof an outermost, or first, concentric channel 16 a. At the outlet of thefirst pumping channel portion 18 a, a diversion channel 22 diverts fluidto a radially inner, or second, concentric channel 16 b and to an inletof a first pumping channel portion 18 b in channel 16 b. Simultaneously,fluid on the second fluid flow path is compressed by rotor bladespassing along a second pumping channel portion 18 a′ forming part of theoutermost, or first, concentric channel 16 a. At the outlet of thesecond pumping channel portion 18 a′, a diversion channel 22 divertsfluid to the radially inner, or second, concentric channel 16 b and toan inlet of a second pumping channel portion 18 b′ in channel 16 b.Respective stripper channel portions 20 a and 20 a′ allow rotor bladesto pass between the inlet and the outlet of pumping channel portions 18a and 18 a′.

Fluid continues along both first fluid flow paths in the same way asdescribed above with reference to the outermost, or first, concentricchannel 16 a until the fluid reaches pump outlets 14 a and 14 b where itis exhausted from the pump 10.

In pump 10, each concentric channel 16 comprises two pumping channelportions 18 and two stripper channel portions 20. However, it will beappreciated that increased pumping capacity will be achieved if onlysome or one concentric channel is provided with this parallel pumpingarrangement. In FIG. 2, a pump 30 is shown in which the two radiallyouter concentric channels each have two pumping channel portions (shownin solid lines) and two stripper channel portions (shown in brokenlines), whereas the two radially inner concentric channels have onepumping channel portion (shown in partially broken lines) and onestripper channel portion (shown in broken lines).

Fluid flows along a first fluid flow path extending from a first pumpinlet 32 a to a single pump outlet 34, and along a second fluid flowpath extending from a second pump inlet 32 b to the pump outlet 34. Atthe radially inner concentric channels, the first and the second fluidflow paths merge.

As with pump 10, fluid flowing on the first fluid flow path travelsalong respective first pumping channel portions 38 a, 38 b in first andsecond concentric channels 36 a, 36 b. At the outlet of the firstpumping channel portion 38 b in the second concentric channel 36 b,fluid is diverted inwardly by a diversion channel 41 to the thirdconcentric channel 36 c and to a secondary inlet 42 in pumping channelportion 38 c. Inlet 42 is situated approximately half way along thelength of pumping channel portion 38 c. Fluid flowing on the secondfluid flow path travels along respective second pumping channel portions38 a′, 38 b+ in first and second concentric channels 36 a, 36 b. At theoutlet of the second pumping channel portion 38 b′ in the secondconcentric channel 36 b, fluid is diverted inwardly by a diversionchannel 41 to the third, or radially inner, concentric channel 36 c andto a primary inlet 44 in pumping channel portion 38 c. Inlet 44 issituated at the start of pumping channel portion 38 c. First and secondfluid flow paths merge at secondary inlet 42. At outlet 46 of pumpingchannel portion 38 c, fluid is diverted inwardly by a diversion channel41 to fourth, or radially innermost, concentric channel 36 d and to theinlet 48 of the fourth pumping channel portion 38 d where the fluid iscompressed over the final stage of the pump 30 and exhausted throughpump outlet 34.

Stripper channel portions 40 c and 40 d allow the passage of rotorblades from the outlets to the inlets of respective pumping channelportions 38 c and 38 d.

Pump 30 provides increased pumping capacity as compared with prior artpump 100 but provides less capacity than pump 10. With the parallelarrangement of fluid flow paths described in relation to FIGS. 1 and 2,pumping capacity can readily be changed by changing the stator of apump. This is because the rotor is the same and the rotor blades are thesame size from pump to pump. For instance, if it is desired to increasethe capacity of pump 100 shown in FIG. 3, the stator can be replaced bythe stator of pump 10 or pump 30. This means that variations in pumpingcapacity can be achieved at relatively lower costs. It will also beappreciated that the pumps shown in FIGS. 1 and 2 achieve increasedcapacity without significant changes in pump size or mass, and withoutsubstantial increases in power requirements.

As shown in FIG. 1, two pumping channel portions are provided in eachconcentric channel. It is possible to provide more than two such pumpingchannel portions in each or one of the concentric channels, providingthe required compression is achieved in each pumping channel portion.

FIG. 1 shows a radial regenerative fluid pump with increased pumpingcapacity. However, the present invention also relates to an axialregenerative fluid pump, in which the concentric channels are arrangedaxially as opposed to radially.

1. A regenerative fluid pump comprising a rotor having rotor blades, anda stator comprising a plurality of concentric channels which comprisepumping channel portions along which said rotor blades move forcompressing fluid between respective inlets and respective outlets ofthe pumping channel portions and stripper channel portions for allowingsaid rotor blades to pass from said outlets to said inlets of thepumping channel portions, wherein at least one of said concentricchannels comprises at least two pumping channel portions and at leasttwo stripper channel portions and wherein one or more radially innersaid concentric channels each comprise a single said pumping channelportion and a single said stripper channel portion.
 2. The regenerativefluid pump as claimed in claim 1, wherein one of said single pumpingchannel portions comprises two inlets.
 3. A stator for a regenerativefluid pump comprising a rotor having rotor blades, the stator comprisinga plurality of concentric channels which comprise pumping channelportions along which said rotor blades move for compressing fluidbetween respective inlets and respective outlets of the pumping channelportions and stripper channel portions for allowing said rotor blades topass from said outlets to said inlets of the pumping channel portions,wherein at least one of said concentric channels comprises at least twopumping channel portions and at least two stripper channel portions andwherein one or more radially inner said concentric channels eachcomprise a single said pumping channel portion and a single saidstripper channel portion.
 4. The regenerative fluid pump as claimed inclaim 3, wherein one of said single pumping channel portions comprisestwo inlets.